I have a Ryobi 18 v 5 amp lithium battery which was attached to a blower but left out in the rain the blower motor still runs

Question edited to add FULL make model (what it is).
Category moved from Washing Machines to Ryobi Trimmer.

Replace the spark plug. Strip and clean the carburetor. Replace the fuel with fresh. But hang on though, the RY40002 is electric and runs with a 40 volt battery, so no spark plug and carburetor! :>D Replace the battery, lubricate everything from the motor to the head. Check the motor with nothing attached to it. The carbon brushes may need replacing or its bearings need greasing.

Ryobi RY40002 40V Power Head and RY15523A Expand-It ...

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Includes (1) RY40002 40V Power Head and (1) RY15523A Expand-It Trimmer Attachment · Compatible with All Ryobi 40V Lithium-Ion Batteries (Sold Separately) ...
US$119.90 · ‎Out of stock

batteries do not like being washed with any liquid

Ryobi P115 is an 18V battery charger. However, Ryobi Manual did not mention the current rating of P115. if the current rating of Ryobi P115 is 50% higher than your 18V Lithium Battery it will charge. but if it's less than or equal, it will not.

You have a weak cell in the battery therefore it isn't producing enough amps. Needs to be replaced.

the wiring maybe disconnected, either at the switch or down near the head of the trimmer

Rebuilding the Lithium batteries is a waste of time and money. For starters the cells cost a minimum of $5 ea and a low power pack takes 5, so now you are in for $25 without doing any work. You can pick up packs on eBay for around $30 - $40 if you shop around. If you know what you are doing, you can strip cells from bad packs and test them to find good ones and then rebuild with those. It can be tricky and you may get mixed results.

Yes, and charge it up occasionally to keep it alive. Lithium batteries are costly and severe cold is not good for any type of battery.

The battery will power your equipment for 30 to 45 minutes, that is normal. What you're thinking of is the lifespan of a lithium battery. It with your battery will last 10 times longer than a regular NiCad battery. So you will be able to charge the battery and use it Hundreds of times before the Battery Life is depleted. Sounds like it's working as designed

the batteries are getting weak,I bet if you buy a new battery and fully charge it your drills will run like your used to.